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 Post subject: Alky cam
 Post Posted: Sat Oct 13, 2012 6:11 pm 
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Location: Stranded in Iowa
I am changing over from gas to alky. I ve been at this a while. With everything else being equal would there be a difference in the choice of camshafts between a race gas engine and a methanol engine?

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 Post subject: Re: Alky cam
 Post Posted: Sat Oct 13, 2012 6:41 pm 
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Dennis I'd make a phone call to Bullet and see what they say about this. I know that methanol will make power at a lower RPM than gas and also that large CID engines don't typically work well with methanol above 7 K RPM or so.

I run both race gas and methanol in mine and I've not seen too much difference between the two performance wise. I've been 140 MPH with both and hight 4.90s too so go figure. And my engine isn't really that large at 434 CID.

One main advantage for methanol, or maybe a disadvantage in cooler climates is that it doesn't produce the heat that gas does. I typically run gas in early spring or late fall because of the heat issue, or rather the lack thereof. ;-)


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 Post subject: Re: Alky cam
 Post Posted: Sun Oct 14, 2012 3:16 pm 
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From what I know of this I would want less difference the between intake and exhaust duration. Something like 4°-6° no more the 8°. Other wise it may be hard to build temp in the engine, and above the piston.

Don

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 Post subject: Re: Alky cam
 Post Posted: Mon Oct 15, 2012 3:40 pm 
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I hope you do not mind me chiming in here. I have built several engines to run alky and gasoline but I also have completed several that people ran only alky and or only gasoline. If you are going to maximize each engine for maximum power, then you will find that you will need to take into account which fuel you are going to use. Going both ways will only provide you with a compromise at best and neither fuel will be maxed. Alky, if built properly, will provide you with 8% to 14% more torques thru out the range. Also normally, you will find the peak torque range elevated upwards a few hundred RPM. You will find the peak HP gain will be dependant on how well the head performs, but will normally be around 7% to 9%. You have to remember that you will be using approximately 2.1 times more fuel with alky and it will crowd out some air thru the intake system and heads. With the carburetor you can easily get around this by going to a slightly larger carb. Not true with the intake and head unless you are already too large. With the intake system, you want to maintain all the heat you can thru out the induction system where as with gasoline it is opposite. Do not coat the underside of the intake to keep temp out. Try to get temp in. Also with alky, you will find that you will have to raise the engine temp so as to help vaporize the fuel and in most cases, but not always, you will need to advance the timing because of the slower burn cycle. In several cases we even went to thermostats to control the engine temp. You will find that most people spread the lobes slightly to keep from so much alky going out the exhaust hole unburned. Speak with John at Bullet as he knows what to do and is a good authority. You will find that many people go too standard tension oil rings to stop so much fuel going into the oil pan so you will have a little more parasitic loss here. With alky, you can run the engine on rich and not see any power loss where as with gasoline , you will see substantial losses. This is a plus with alky as you can set it up for cool morning and hot day running and cool night passes and not make changes. Much more stable for that. There are other items to search for, but this should give you a little insight as to what you will encounter.
reed

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